11 (b) Martin does another experiment. He investigates how the pH of an acid affects the rate of corrosion of one alloy. The alloy reacts with the acid to produce hydrogen gas. Martin measures the rate at which the hydrogen gas is made. He does this at three different pH values. He repeats his experiment five times at each pH and then plots a graph of his results. Look at his graph.
1.0 rate of production of hydrogen gas in cm3 / hour 0.5
0
3
4
5
6
pH (i)
What was the highest rate of production of hydrogen gas that Martin measured at pH 5? answer ............................................... cm3 / hour
(ii)
[1]
At which pH did Martin get the most repeatable results? ...................................................................................................................................... [1]
(c) Aluminium, Al, reacts with sulfuric acid, H2SO4. Aluminium sulfate, Al 2(SO4)3, and hydrogen, H2, are made. Write a balanced symbol equation for this reaction. .............................................................................................................................................. [2]
Š OCR 2015
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